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In Reply to: RE: the battery is at 13.15 volts right now posted by thump on January 18, 2017 at 01:18:35
the terminals are no longer corroded. i swapped the screw & nut for new ones and dropped the washers. the only thing corroded now is the charger's negative alligator clip."testing" things is hardly ever possible at goodwill unless you bring your own interconnects & cables and if the have an amp, there's no speakers and if the have speakers, no sources or amps etc. i just don't like buying from them after having to toss a heavy $15 door-stop, i mean receiver stuck in fault mode, because it was too heavy to carry a 2nd time, but everything lit up nice on it until i made the "mistake" of connecting speakers at home. i'd rather buy used gear at a place that properly tests it and guarantees it. i think the charger was just $12, and LOOKED to be in new condition with a box. i doubt it's still there though.
everything worked fine for over an hour last night after the charger indicated a 75%, i believe, charge, until my media player's battery went dead. i do think you were right about the amp undervolting. i gave the battery around a full day's charge after that, and haven't had any issues since. i might have been drawing a lot more power than i thought when the sub was still hooked up.
there's ANOTHER issue i have to resolve as the cone made a plastic buzzing noise on a couple tracks with really deep bass when i turned the mains up to something approaching a normal listening level with the sub bridged and its input maxed plus 50% bass boost too i think. i'm thinking it MIGHT be overexcursion related as it could be an impact related buzz, but my 1st guess was a loose dustcap.
i just powered the amp back up with a low volume load, and the voltage dropped to 12.87v quickly and got down to 12.82v within a few more minutes.
Edits: 01/18/17 01/18/17Follow Ups:
in looking up how to measure watts, i got the multimeter version of V x A = W, so i decided to give it a go and right away got a very weird result. measuring the speaker out allen screws, i get -.09v (polarity correct) on the left channel and +.03v to +.04v on the right @20v meter setting. as i suspected, the left channel IS lower in volume, but the right channel is wired out of phase too.i got -.22a on the left and +.09a on the right at the 10 amp setting on the meter.
BTW, if i'm doing the math right, that = -3.98w on the left channel and +.72w on the left channel, right?
if the front mains left channel is wired out of phase, then maybe the rear channel's left is too so that would mean i MIGHT have been bridging the sub L positive to R positive. instead of L- to R+. now i wonder if MAYBE the buzzing was related to the sub bottoming out. THAT would cause a buzz i bet.
i reversed the inputs in case it had anything to do with the media player or the cables and got the same readings.
Edits: 01/18/17 01/18/17
The small DC voltages don't mean anything, just slight leakage at the output stage of the amplifier. If you see bass deflected (pushed in or out) with no sound, then you have a problem. Follow your wires to be sure amplifier + to speaker (or crossover) + and the phase will be correct. Don't know what kind of speaker wire you are using, but most have some indicator so you can determine one lead from the other at both ends. On lamp cord, one has small ridges.
Over 13+ volts is battery float voltage. After a few minutes of playing it will drop to 12 something, that is normal. To see if the problem you are having is battery drain, play it until you hear the problem and check the DC voltage at the amplifier.
If you continue to have problems and want to talk about it, I accept e-mails, send me phone number and I will call you.
Prolly not helpfull :-)
In My dabblings with D amps I will only say these are too often Junk.
Buy Cheap = Buy twice or if Obtuse; repeatedly
You could try a Car Battery yup yank your cars' battery and see what happens when it's thge power source.
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